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[narrator] There is a general consensus among geologists
that the earth is at least four and a half billion years old. Fragments of this inconceivably
distant past dominate the surface of Big Bend Ranch State Park. It’s a place shaped and
scarred by eons of geologic havoc. Shifting continents, volcanoes, faulting and erosion
have all at one time or another played a role in the formation of this landscape.
[narrator] These rocks form part of a giant puzzle that
contains the history of our planet. Only, the puzzle has a lot of missing pieces.
[splashing water]
[narrator] It’s the job of the geologist to put this
fractured puzzle together. Dr. Kevin Urbanczyk of Sul Ross State University has been working
in and around Big Bend Ranch State Park since 1984.
[Dr. Urbanczyk] Man this water is just glassy, smooth.
[narrator] For the last few years Kevin has been taking
his students on field trips into this desert region. The Rio Grande skirting the southern
boundary of the park has provided them with a prime setting for a floating laboratory.
[Dr. Kevin Urbanczyk] The dip out here is the rocks are not flat,
they’re tilted to the west a little bit. So if you take a series of layers and tilt
them to the west, and then cut through them with a river like this, the river is cut down
through these things, then we’re floating into older and older rocks. Cause remember
the older ones are always at the bottom, you tilt it and then cut it through horizontally.
As we float, we started in rocks that were about 28 million years old, we floated into
stuff that might be about 29 by now.
[John Alcott] The professor can put everything into perspective
and hit on things that were hit on in class. And you can actually relate what’s in the
classroom to what’s out in the field.
[Shea O’Briant] You can textbook yourself all over the place
but you got to go out and look at it and actually see it. And Kevin he knows the area real well
so he comes down and he tells us everything we need to know. I’m finally learning all
the formation names. So yeah, it’s been a lot of fun. We do probably 10 trips a year
with the geology department at Sul Ross.
[Dr. Urbanczyk] So it’s been really successful. We’ve
introduced this canyon in particular to a lot of students, introductory geology students
at Sul Ross who never would have done this, never would have floated through these canyons.
[narrator] Some of the oldest rocks in the park are found
within the Solatario. This is called ‘Tesnus Shale’.
[Dr. Urbanczyk] The Tesnus is interpreted as being Carboniferous
in age. Carboniferous being one of the periods of the Paleozoic about 300 or 320 million
years old or so.
[narrator] Once an ancient sea bottom, this section of
deep ocean sediment was caught between two colliding tectonic plates, approximately 280
million years ago. When the plates came together the sediment was squashed, tilted and thrust
onto the American continents. This section of the Tesnus has since been exposed by erosion.
[Dr. Urbanczyk] Ok, this is pieces of this tesnus shale, and
it represents basically solidified or litified mud. But it’s a sedimentary deposit that’s
300 million years old.
[narrator] Between 25 and 42 million years ago at least
seven volcanoes were active in the Big Bend region. This is Guale Mesa, the spot where
the ash, lava and mud flows from five of those volcanoes came together.
The actual cones of the volcanoes have long since eroded away, leaving behind only scattered
clues of their existence.
[Dr. Urbanczyk] It’s wonderful that the state has, does
own this property because it provides scientists access to this natural laboratory. In west
Texas in general or access to private property has become restricted, and so we have Big
Bend National Park and Big Bend Ranch really to work with.
[narrator] As the pieces of this fractured, global puzzle
come together, the window to our earth’s history becomes clearer. Geologists looking
through that window at Big Bend Ranch State Park become witnesses to events that occurred
over billions of years. Meanwhile, this landscape of rock and canyon waits patiently for the
next big shake up of the primeval puzzle.